Morphology,Thermal and Mechanical Properties of Biodegradable Poly(butylene succinate)/Poly(butylene adipate-co-terephthalate)/Clay Nanocomposites

Sodium montmorillonite (Na-MMT) was successfully modified by octadecylamine (ODA) through a cation exchange technique that showed by the increased of basal spacing of clay by XRD. The addition of the organoclay into the PBS/PBAT blends produced intercalated-type nanocomposites with improvements in tensile modulus and strength. The highest tensile strength of nanocomposite was observed at 1 wt% of organoclay incorporated. A TGA study showed that the thermal stability of the blend increased after the addition of the organoclay by 1 wt%. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes smoother with presence of organoclay.     

SEBS弹性体对聚丙烯形貌、力学性能和结晶性能的影响

采用SEBS(氢化SBS)弹性体增韧PP.利用SEM、DSC、熔体指数、力学性能测试等研究不同SEBS含量的PP/SEBS共混物的力学性能、微观形态结构以及结晶性能.结果表明:SEBS可均匀分布在基体中,改善PP的加工流动性;SEBS的加入使得PP的球晶尺寸减小,结晶度降低;随着SEBS含量增加,共混物的冲击韧性有较大幅度的提高,而屈服强度略有下降:当加入25%的SEBS时,PP/SEBS共混物的冲击强度比纯PP提高近26倍,拉伸强度则仅仅降低23%.     

Enhanced Tensile and Dynamic Mechanical Properties of Thermoplastic Natural Rubber Nanocomposites

The melt compounding technique was employed to prepare thermoplastic natural rubber (TPNR) nanocomposites. The maleic anhydride grafted polyethylene (MA-PE) as a coupling agent was used to improve the filler-matrix interfacial adhesion. TPNR were prepared in the ratio of (70:20:10) from linear low-density polyethylene (LLDPE), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer between the matrix. The composites were prepared using the in-situ method at the optimum processing parameter at 140°C with 100 rpm mixing speed and 12 minutes processing time. The results of the tensile test showed that the optimum of clay loading was obtained at 4 wt%. Dynamic mechanical analysis (DMA) was performed to investigate the thermomechanical properties of the composites. The results show that the addition of organoclay has improved the storage modulus (E′) and loss modulus (E′′) of TPNR nanocomposites. The α transition peaks was also shifted to the higher temperature. However, nanocomposites with MA-PE demonstrated higher, E′ and E′′ compared to TPNR nanocomposites without MA-PE. The TEM results show good clay dispersion with a combination of intercalated-exfoliated structure in the TPNR matrix.     

Polypropylene/Organoclay Nanocomposites: Effects of Clay Content on Properties

The effects of clays as nanoscale fillers have been rarely addressed. Influence of the amount of organoclay (ranging between 1 and 10 wt.%) on the nanocomposites structure, i.e., intercalated or exfoliated, and on the enhancement of mechanical, rheological and morphological properties of polypropylene (PP) nanocomposites was studied in this work. The fundamental material characterization was conducted using XRD, SEM, TEM, DSC, POM, DMTA as well as RMS. Overall mechanical properties determined by tensile tests showed improvements. DSC and POM results demonstrated decrease of nanocomposites crystallinity. XRD and TEM Showed intercalate/exfoliate structures in the resultant nanocomposites.     

熔体流动性对聚丙烯材料结晶度和力学性能的影响

用X射线法测定了不同熔体流动速率下聚丙烯材料的结晶度。结果表明 ,材料熔体流动性的变化将会影响其结晶行为 ,随熔体流动速率降低 ,结晶度越低 ,拉伸强度下降 ,断裂伸长率增大。熔体流动性对冲击强度的影响较为复杂 ,发现存在一极大值 ,该极值的出现预示可能与分子量和分子量分布的变化有关。     

Effect of Nanoparticle Surface Treatment on Nonisothermal Crystallization Behavior of Polypropylene/Calcium Carbonate Nanocomposites

Polypropylene (PP)/CaCO₃ nanocomposites were prepared by melt-blending method using a Haake-90 mixer. The CaCO₃ nanoparticles were surface modified with a coupling agent before compounding. A fine dispersion of the modified nanoparticles in the nanocomposites was observed by transmission electron microscopy (TEM). Effects of surface treatment of CaCO₃ nanoparticles on the nonisothermal crystallization behavior and kinetics of PP/CaCO₃ nanocomposites were investigated by differential scanning calorimetry (DSC). Jeziorny and Mo methods were used to describe the nonisothermal crystallization process. It was shown that the crystallization temperature of the nanocomposites increased due to the heterogeneous nucleation of the surface-treated nanoparticles. It was found that the nanoparticles modified with a proper content range of coupling agent could facilitate the nonisothermal crystallization of the nanocomposites under certain conditions (the cooling rate and the relative degree of crystallinity). This may be a potential application for the crystallization controlling of composites in manufacturing. In addition, the activation energy of crystallization for the nanocomposites and the nucleation activity of the nanoparticle were estimated by using Kissinger and Dobreva's methods, respectively. It could be concluded that the surface-treated nanoparticles had a strong nucleating activity, which caused the decrease of the activation energy of the nanocomposites.     

Study of the Mechanical,Thermal Properties and Morphology of Polypropylene Nanocomposites in the Presence of Compatibilizer

In this work, the mechanical, rheological, and thermal properties and morphology of a polypropylene matrix reinforced with single-walled nanotubes (SWNTs) were investigated. Polypropylene-grafted-maleic acid was used as a compatibilizer to promote SWNTs dispersion. Compared to uncompatibilized nanocomposites, the tensile modulus of the material increased considerably when nanotubes and compatibilizer were employed. The rheological characterization results revealed that addition of SWNTs increased the storage modulus and complex viscosity at low frequencies. SEM revealed that the SWNTs were uniformly distributed when low concentrations of SWNTs were employed. The results of DSC indicated that the addition of SWNTs increased the crystallinity of nanocomposites.     

成核剂对聚丙烯结晶形态和力学性能的影响

研究了聚丙烯(PP)／成核剂共混物的结晶形态及力学性能。结果表明：加入成核剂后，提高PP的结晶温度，加快了结晶速度，使PP球晶细化；成核剂用量在0—0．2份之间时，PP的冲击强度、拉伸强度、硬度、热变形温度均随成核剂用量的增加而提高。     

The Effect of Multiple Compatibilizers on the Impact Properties of Polypropylene/Polystyrene (PP/PS) Blend

Effects of compatibilizers on impact properties of polypropylene/ polystyrene (PP/PS) blends were studied and carried out through melt blending using co- rotating twin-screw extruder. A combination of two compatibilizers, maleic anhydride grafted polypropylene (PP-g-MA) and styrene maleic anhydride (SMA) was applied into PP/PS blends. Results from the Izod impact strengths, SEM observations and contact angle measurements in PP(50)/PS(50) blends indicated a better compatibilization effect with the use of dual compatibilizers. This was most probably due to improved adhesion between phases in PP/PS blend systems. The use of dual compatibilizers in the blend compositions produced higher impact properties in the PP/PS blend systems compared to single compatibilizer system.     

Improvement of Mechanical Properties of Jute Fibers-Polyethylene/Polypropylene Composites: Effect of Green Dye and UV Radiation

Jute-reinforced polyethylene (PE), polypropylene (PP) and mixture of PP/PE composites were prepared. It was found that 90% PP and 10% PE matrices based jute reinforced composites performed the better results. UV radiation at different intensities was applied both on matrices and jute. Mechanical properties of the irradiated jute- and matrices-based composites were found to increase significantly. Optimized jute fabrics were also treated with different concentrations of green dye (0.1–1%, w/w) with 2% K₂O₈S₂ in methanol solution for 2–8 min. A composite made of 0.5% green dye jute (5 min soaking time) and irradiated matrix showed the best mechanical properties.     

Preparation and Mechanical Properties of Polypropylene/Maleic Anhydride Compatibilized Polypropylene/Organo-Vermiculite Nanocomposites

Polypropylene/Maleic anhydride compatibilized polypropylene (MPP)/Organo-Vermiculite nanocomposites with different clay loadings were prepared via melt mixing using a twin screw extruder. The vermiculite (VMT) was pre-modified with Maleic anhydride (MA) by ball milling. The mechanism of VMT modification by MA was discussed. The resultant PP/MPP/OVMT nanocomposites possess an intercalated or exfoliated structure as confirmed by both wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The mechanical property tests show that the tensile strength, flexural strength of these nanocomposites increase dramatically with the OVMT loading; the fracture toughness remain almost unchanged, and the Charpy impact strength decrease slightly.     

Solution Intercalation and Relaxation Properties of Maleated Polypropylene/Organoclay Nanocomposites

In this work we report the investigation of the dynamics of maleic anhydride grafted polypropylene (PPgMA) and PPgMA-based nanocomposites by means of dielectric relaxation spectroscopy (DRS) and dynamic mechanical thermal analysis (DMTA). After characterization of neat PPgMA, we study the effect of organically modified silicate filler on the dynamics of PPgMA with dynamic mechanical thermal analysis. Our results suggest that the β-relaxation process, corresponding to the glass transition of PPgMA, is affected by the clay loading. The glass-transition temperature of PPgMA increases in a composition with filler content of 30 wt.%, probably because of polymer-filler interactions, which reduces the polymer chain mobility.

In the nanocomposite materials a separate high temperature process due to Maxwell-Wagner-Sillars (MWS) polarization was observed with dielectric relaxation spectroscopy.     

Morphology, thermal stability and rheology of poly(propylene carbonate)/organoclay nanocomposites with different pillaring agents

Unpillared montmorillonite PGV and five organoclays (Nanocor's Nanomer I.44P, I.24TL and I.34TCN and Southern Clay Product's C25A and C30B) were high shear melt-blended (2.5 wt%) into poly(propylene carbonate) (PPC). Solubility parameters of the clay pillaring agents versus that of PPC were used to predict clay/PPC miscibilities and these were compared to XRD and TEM nanoclay dispersion measurements. Clays I.34TCN and C30B, with the highest predicted pillaring agent/PPC miscibilites, had partially exfoliated morphologies. Clays I.24TL, C25A and I.44P, with pillaring agents predicted to be less PPC miscible, were less highly nanodispersed. Quaternary ammonium pillars with two 2-hydroxyethyl groups promoted the best nanodispersion in PPC. 12-Aminododecanoic acid (in I.24TL) promoted the intercalation. Dimethyl dialkyl quaternary ammoniums (in I.44P and C25A) were less effective. Organoclay dispersion improved the thermal stability. The PPC/I.24TL nanocomposite, with the most stable 12-aminododecanoic acid pillar, was the most thermally stable (PPC/I.34TCN and PPC/C30B were the second and third). The nanocomposites exhibited narrower linear viscoelastic zones than PPC and solid-like behaviors in these linear zones.     

Rubber‐toughened polypropylene nanocomposite: Effect of polyethylene octene copolymer on mechanical properties and phase morphology

Rubber‐toughened polypropylene (PP)/org‐Montmorillonite (org‐MMT) nanocomposite with polyethylene octene (POE) copolymer were compounded in a twin‐screw extruder at 230°C and injection‐molded. The POE used had 25 wt % 1‐octene content and the weight fraction of POE in the blend was varied in the range of 0–20 wt %. X‐ray diffraction analysis (XRD) revealed that an intercalation org‐MMT silicate layer structure was formed in rubber‐toughened polypropylene nanocomposites (RTPPNC). Izod impact measurements indicated that the addition of POE led to a significant improvement in the impact strength of the RTPPNC, from 6.2 kJ/m² in untoughened PP nanocomposites to 17.8 kJ/m² in RTPPNC containing 20 wt % POE. This shows that the POE elastomer was very effective in converting brittle PP nanocomposites into tough nanocomposites. However, the Young's modulus, tensile strength, flexural modulus, and flexural strength of the blends decreased with respect to the PP nanocomposites, as the weight fraction of POE was increased to 20 wt %. Scanning electron microscopy (SEM) was used for the investigation of the phase morphology and rubber particles size. SEM study revealed a two‐phase morphology where POE, as droplets was dispersed finely and uniformly in the PP matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3441–3450, 2006     

Mechanical and Antibacterial Properties of Polypropylene/Polyamide 6 Blends-TiO2 Nanocomposites

Polypropylene/Polyamide 6 (PP/PA6) blends-TiO₂ nanocomposites have been prepared via melt blending PP/PA6 with TiO₂ nanoparticles, which were pretreated with toluene-2,4-di-isocyanate. The functionalized-TiO₂ can react with the terminal amino and carboxyl groups at PA6, interfacial interaction and compatibility between TiO₂ and matrix have been greatly improved resulted in higher tensile and impact strength than that of those filled with pristine TiO₂ or pure PP/PA6 blends, and they have strong antimicrobial abilities against Bacillus subtilis, Staphylococcus aureus and Escherichia coli. The average efficiency of antibacterial is over 90% within 2.0 h. Mechanical and antibacterial properties can achieve their maximum with 3.0 wt%TiO₂.     

Oxygen Barrier Properties of New Thermoplastic Natural Rubber Nanocomposites

Nanocomposites of linear low-density polyethylene (LLDPE)/natural rubber (NR)/liquid natural rubber (LNR) blend denoted as TPNR with montmorillonite-based organoclay (OMMT) were prepared using melt blending method. The melt blending of LLDPE/NR/LNR with a composition of 70:20:10 formed blends. For better dispersion of nanoclay in the TPNR blend, MA-PE was used as a coupling agent. The nanoclay dispersion was investigated by X-ray diffraction (XRD), and a novel method using permeability measurements data in a permeability model. The measured d-spacing data proved a good dispersion of nanoclay at low clay contents. The permeability model for flake-filled polymer was used to estimate the aspect ratio of nanoclay platelets in the blend nanocomposites. The oxygen barrier property of the TPNR blend improved about two-fold by adding only 2 wt% of organoclay. Differential scanning calorimetry showed an increase in cystallinity up to 20% suggesting an increase in spherulite growth, by the increased in melting temperature. The increase in the barrier property of the blend with the induction in crystallinity indicates the dominant role of organoclay platelets in barrier improvement. Scanning electron micrographs of tensile fracture surface of the nanocomposite, exhibited a very ductile surface indicating a good compatibility of LLDPE and NR and also, a possible contribution of nanoparticles to the deformation mechanism, such as extensive shear yielding in the polymer blend. The transmission electron micrograph, showed an intensive intercalation structure and exfoliation structure with the presence of MA-PE.     

改性高岭土/聚丙烯复合材料的热性能及非等温结晶行为研究

以自制的剥离高岭(MK)、原高岭土(K)以及聚丙烯(PP)和马来酸酐接枝聚丙烯(PP-g-MA)等作为基本原料,通过熔融挤出、注塑成型,制备PP复合材料。采用XRD、DSC、TG研究复合材料的非等温结晶行为、结晶动力学以及热降解性能。结果表明:高岭土的加入,使结晶温度、结晶度、热稳定性都有所提高,且结晶速率加快,具有异相成核作用。与原高岭土相比,改性高岭土更能促进PP复合材料的PP异相成核,促进PP稳态晶型(α晶型)的转变,结晶速率较快。与纯PP和PP/PP-g-MA复合材料相比,PP/改性高岭土复合材料的结晶峰温度、最大热降解温度分别提高了16.7、7.8、9.7、12.6℃。     

PBT/官能化聚烯烃弹性体共混体系的力学性能与相形态

考察了马来酸酐接枝乙烯-辛烯共聚物（POE-g-MAH）和乙烯-丙烯酸甲酯-甲基丙烯酸缩水甘油酯三元共聚物（E-MA-GMA）对聚对苯二甲酸丁二醇酯（PBT）的增韧作用。结果表明,未接枝的POE弹性体对PBT缺口冲击韧性的改善作用不大。两种官能化聚烯烃弹性体（E-MA-GMA、POE-g-MAH）对PBT具有显著的增韧作用。当弹性体用量分别达到8．5％和10％以后,共混物都各自出现明显的脆／韧转变现象。这意味着在达到同样的冲击韧性时,PBT／E—MA—GMA共混体系的拉伸强度损失较小。SEM显示,PBT／E—MA—GMA共混体系中分散相具有更细微的分散,有效地诱导PBT基体产生银纹和剪切屈服,消耗大量的冲击能。     

Synergistic Effect of Epoxy/Organophilic Montorillonite Nanocomposites and Triphenyl Phosphate on Flame Retardance Enhancement of Polypropylene

Epoxy/organophilic montorillonite (Epoxy/OMMT) nanocomposites were prepared by epoxy intercalated into the interlayer of OMMT, and flame retardant polypropylene (PP) was obtained with Epoxy/OMMT nanocomposites and triphenyl phosphate (TPP) mixture as flame retardant agent. The effect of epoxy sorts, mass ratio of OMMT and Epoxy, and the contents of Epoxy/OMMT and TPP on properties of PP were studied. It was found that there is a remarkable synergistic flame retardant effect of novolac epoxy/organophilic montorillonite (NE/OMMT) and TPP on PP. Flame retardant PP with oxygen index (OI) value of 36.5%, peak heat release rate (PHRR) of 654 kW/m², notched Izod impact strength of 6.93 kJ/m² and tensile strength of 30.56 MPa was obtained when the mass ratio of OMMT and NE is 5:100, the content of NE/OMMT and TPP is 13.33 and 6.67 wt.%, respectively. The materials were characterized via X-Ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectrum (FT-IR), and thermogravimetry (TG). The XRD results and TEM photograph indicate OMMT is exfoliated in PP matrix when the mass ratio of OMMT and NE is lower than 10:100. The TG results show the evaporation of TPP is greatly hampered by NE/OMMT nanocomposite. PP with NE/OMMT-TPP has an onset weight loss temperature 31.7°C higher than PP with NE-TPP because of the shielding effect of OMMT layers. The FT-IR spectra indicate phosphoric acid is generated from TPP and carboxylic acid and phenyl ether are generated from NE under thermal degradation, which further results in the formation of thermally stable char. This charring process is also affirmed by the wide thermally stable zone at 380–550°C in TG curves of PP with NE/OMMT-TPP or NE-TPP.     

Mechanical and Electrical Properties of Jute Fabrics Reinforced Polyethylene/Polypropylene Composites: Role of Gamma Radiation

Jute fabrics reinforced polyethylene (PE), polypropylene (PP) and mixture of PP+PE matrices based composites (50 wt% fiber) were prepared by compression molding. It was found that the mixture of 80% PP + 20% PE hybrid matrices based jute fabrics reinforced composites performed the best results. Gamma radiation (250–1000 krad) was applied on PP, PE and jute fabrics then composites were fabricated. The mechanical properties of the irradiated composites (500 krad) were found to increase significantly compared to that of the non irradiated composites. Electrical properties like dielectric constant, loss tangent and conductivity with temperature variation of the composites were studied.